1. Field of the Invention
This invention relates to loom harnesses and, more particularly, to an improvement in a heddle rod hanger.
2. Description of the Prior Art
The advent of high-speed looms with substantially greater capability in cloth width and the use of a much greater amount of frames in the loom created the necessity of using extruded metal frame rails of small cross-sectional dimensions and of light weight so as to be compatible with logical mechanical capabilities and space limitations of the loom. To avoid sliding contact of adjacent frame rails nose guides were particularly desirable.
Early types of extruded metal rail frames incorporated integral heddle rods as a part of the rail. The desirability of heddle rod vertical adjustment led to the mounting of adjustable heddle rod supports within cutouts in the bottom of the top rail and the top of the bottom rail. These cutouts were of necessity of such a size that they substantially weakened the rails and caused buckling and tearing of the rails when in use.
The subsequent development of plastic nose guides with integral extensions of the plastic to provide a support on the nose guide for the attachment of a heddle rod came into use to avoid such substantial cutouts and to also perform the shedding action of a nose guide.
The thin cross section of these plastic extensions for the support of the heddle rods made them subject to stresses in action more than the ability of the plastic to withstand and they often broke apart at some point in the extension leaving the heddle rod unsupported and thereby stopping the use of the loom until the support was replaced. An early type of this support was a one-piece hanger, installed upon the rail by sliding it along the rail from a dismantled rail end. This entailed removing a great many frame components when it was necessary to replace a broken hanger. This difficulty of replacement led to the development of a one-piece plastic hanger with one end split in order to place the hanger on a rail without inserting it from one end. The split end of the hanger was held in closed position by means of fasteners, such as rivets or screws.
Attempts to preclude longitudinal movement of the hanger along the rail when the loom harness was in use included placing setscrews in the hangers and welding metal studs to the top and bottom of the rail. The cross-sectional area of the studs was too small to affort a dependable weld and the setscrews at times become loosened. Eventual attempts to solve this problem led to the practice of using rivets for fastening the heddle rod to the plastic extension which precluded lateral movement of the hanger upon the rail but necessitated the drilling out of the rivets to separate these parts in the event of breakage. Such operation almost always caused the mandatory removal of the frame from the loom.
The use of rivets to fasten the heddle rod to the plastic hanger extension often resulted in the breakage of the plastic around the rivet due to insufficient wall thickness of the plastic at this point due to the high speed vertical pounding action of the frames in motion. Space limitations govern the wall thickness of the extension in the proportion to space requirements of the associated heddles hanging from the heddle rod with the required movability clearances entailed within the narrow relationship of adjacent frame rails.
The use of an easily removable heddle rod was desirable for convenience and speed of repair but the fragility of the plastic in small cross-sectional area at this connection point was such that it led to further danger of breakage when the connection of heddle rod to hanger was made entirely of plastic in the configuration required by the usual horizontal slip joint connection of these parts.
Recent plastic hangers, which are held in closed positions upon the rails by means of integral snap fasteners, moulded into the hanger, have been devised. However, such fasteners at times become separated as a result of high speed vibrations of the frame, in operation. These hangers still use rivets between the heddle rod and the plastic projection to preclude lateral movement of the hanger along the rail. Such above described devices are shown in the patents to Kramer, U.S. Pat. No. 3,417,788; Kaufmann et al., U.S. Pat. No. 3,470,920; and Kramer et al., U.S. Pat. No. 3,901,282.